Some who bought CD keys for Modern Warfare 2 - no physicial media in other words - from import resellers have seen their access to the game vanish, as Activision has apparently asked Valve to ban such keys.

VE3D, which spotted the thread, points out that calling the key sales "illegitimate" is not entirely true. The keys are typically sold legally in Asia and other territories and while game makers try to ban it, their ability to do so is not absolute. Of course, the interest is clear: The keys being sold cost less than the full game, and both publisher and digital distributor stateside want to protect their bottom lines.